A device for the interconnection of RS485 terminal blocks (bus bars). SW485 enables up to nine RS485 terminal blocks to be connected in a star topology. All the lines are equal. When data are received by any line, they are sent to all the other lines.
Figure 1: Block diagram of SW485 and connection of several devices (example)
Data from individual lines are only processed by logical circuits. Data received by any of the lines are sent to all the other lines. Individual lines have no buffer for data receipt.
When data arrive almost simultaneously to two lines, the system receives the data whose beginning was first registered. The other lines switch to "Transmission" and start to transmit the data. After the data receipt has been completed the system waits for a configured period of time (a so called "Switching Delay"). After this period has elapsed, all the lines switch to "Receipt" and wait for data to come.